Reading Data Recovery — UK No.1 RAID-1 (Mirror) Data Recovery Specialists (25+ years)

When mirrored storage fails, our controller-aware, clone-first workflow protects your originals and maximises your recovery outcome. We stabilise each member disk (HDD/SSD), take hardware-level images, compute mirror divergence (which blocks differ and why), reconstruct the upper stack (mdadm/LVM/Storage Spaces/CoreStorage/APFS, ZFS/Btrfs datasets) and repair filesystems (NTFS, XFS, EXT, ReFS, HFS+, APFS, exFAT) on read-only images.
To send your media: place each drive in an anti-static bag inside a padded envelope or small box, include your contact details/case reference, and post or drop-off for a free diagnostic.

Leading NAS brands used in the UK (and representative popular models)

1. Synology — DS224+, DS423+, DS723+, DS923+, DS1522+, RS1221(RP)+, RS3621xs+

2. QNAP — TS-233, TS-464, TS-873A, TVS-h674, TS-1253U-RP

3. Western Digital (WD) — My Cloud EX2 Ultra, PR4100, My Cloud Home Duo

4. Buffalo — LinkStation 520, TeraStation 3420/5420/5820

5. NETGEAR — ReadyNAS RN214/RN424, RR2304, RN528X

6. TerraMaster — F2-423, F4-423, T9-423, U4-423

7. ASUSTOR — AS5304T (Nimbustor 4), AS6704T (Lockerstor 4), AS6508T

8. LaCie (Seagate) — 2big Dock, 5big (business lines)

9. iXsystems — TrueNAS Mini X/X+, TrueNAS R-Series

10. Lenovo/Iomega (legacy) — ix2/ix4, px4-300d, px12-450r

11. Thecus (legacy) — N2810, N4810, N5810PRO

12. Drobo (legacy/discontinued) — 5N/5N2, B810n

13. D-Link — DNS-327L, DNS-340L

14. Zyxel — NAS326, NAS542

15. QSAN — XCubeNAS XN3002T/XN5004T

RAID-1 capable rack/server platforms we routinely recover (examples)

1. Dell PowerEdge — R650/R750/R740xd, T440

2. HPE ProLiant — DL360/380 Gen10–11, ML350 Gen10

3. Lenovo ThinkSystem — SR630/SR650, ST550

4. Supermicro SuperServer — SYS-1029/2029/1114 families

5. Cisco UCS C-Series — C220/C240 M6

6. Fujitsu PRIMERGY — RX2540 M6, TX2550 M5

7. ASUS Server — RS520/RS720-E11

8. GIGABYTE Server — R272/R282

9. Synology RackStation — RS1221(RP)+, RS3621xs+

10. QNAP Rackmount — TS-873AU-RP, TS-1253U-RP, TVS-h1288X

11. Promise VTrak/Vess — E5000/R2000

12. Nexsan — UNITY/E-Series

13. NetApp FAS/AFF (NAS roles) — FAS27xx/AFF A250

14. Dell PowerVault NX — NX3240/NX440

15. HPE StoreEasy (rack) — 1660/1860

75 RAID-1 issues we recover — with the lab method we use

Format: Problem summary — How we resolve it (technical)

Disk / Media (HDD/SSD)

1. One mirror disk failed (array degraded) — Clone the weak member with head-zoned, short-block imaging; use the healthy member image as the basis; fill any unique readable blocks from the cloned partner.

2. Both members weak in different places — Interleave imaging passes across heads/zones to harvest complementary sectors; composite a “best-of” basis image guided by file-system journals.

3. Head crash on a member — Donor HSA swap → low-stress imaging; trust the counterpart for disagreeing blocks; only use rescued unique sectors after journal/time validation.

4. Spindle seizure — Platter migration to a matched donor, servo alignment, clone; compare with partner to select the newest coherent dataset.

5. Translator corruption (0 LBA / no access) — Rebuild translator from P/G-lists and defect tables; clone; continue mirror analysis.

6. Service-area firmware module damage — Repair SA modules (adaptives, microcode, defect lists), then clone; cross-validate blocks against twin.

7. SMR member stalls/realloc storms — Disable relocation on the imager; sequential passes; rely on the CMR/other member where they disagree.

8. Surface media flaking in bands — Head-map and reduce load; carve unaffected bands; fill from twin where consistent.

9. Intermittent read timeouts across both disks — Create a divergence heatmap; trust “agreeing” blocks; arbitrate disagreeing ones using FS transaction order.

10. Bad sector avalanche after power loss — Skip-on-timeout with progressive re-read; reconstruct from the other member for torn sectors using journal hints.

11. SSD retention loss (TLC/QLC) — Temperature-assisted multi-read + majority vote; if FTL lost, chip-off + ECC/XOR and L2P mapping rebuild; prefer blocks that match FS logs.

12. SSD controller SAFE/recovery mode — Vendor admin imaging; failing that, raw NAND dump and remap; reinject the virtual image for mirror selection.

13. Preamp failure (silent or buzzing HDD) — HSA replacement; per-head imaging; treat as supplementary source only if more recent than peer.

14. Media contamination (dust/water event) — Mechanical remediation, platter cleaning, conservative clone; rely on partner for contested blocks.

15. Thermal throttling (NVMe) corrupting reads — Admin-command imaging, controlled thermals, then compare against counterpart to decide truth.

16. Uncorrectable ECC on both members for same LBAs — Carve from snapshots/unallocated slack; reconstruct structured data (e.g., DB pages) using internal redundancy.

Electronics / Power

17. PCB blow/TVS diode short — Donor PCB with ROM transfer; current-limited spin-up; clone; validate against twin.

18. Power surge took out both PCBs — Rail repair/ROM moves; clone each; choose coherent generation by FS journals.

19. Repeated spin-up/down (brown-out damage) — Windowed imaging with gentle start/stop; use other member to arbitrate torn writes.

20. NVMe mapping corruption after brown-out — Controller table repair or raw NAND→L2P rebuild; continue logical repair on the re-built namespace.

Controller / HBA / Enclosure / Metadata

21. Hardware RAID says “optimal” but files corrupt — Bypass controller; image raw members; rebuild mirror in software; pick basis by journal recency and clean-shutdown flags.

22. mdadm reports “clean” while contents differ — Ignore status; compute divergence/diffmaps; choose the side that matches FS transaction IDs.

23. Backplane SAS link CRC storms — Rehost on a known-good HBA/backplane; re-image with CRC counters; discard suspect reads.

24. 512e vs 4Kn mismatch between members — Normalise sector size in the virtual layer; realign GPT/partitions before mirror arbitration.

25. Auto-resync went the wrong way — Stop writes; roll back to pre-resync generation using superblock/event counters; recover from the last coherent side.

26. Write-intent bitmap stale/misleading — Base decisions on FS journals/logs rather than bitmap; rebuild by content validation.

27. Foreign import overwrote metadata — Carve older superblocks/GPT; assemble earlier generation and ignore the foreign set.

28. USB bridge truncated end-of-disk metadata — Re-image via SATA/SAS HBA exposing full LBA; restore backup GPT/superblocks; proceed.

29. Controller migration (vendor change) — Translate metadata (e.g., controller mirror→mdadm); assemble/mount RO outside the controller.

30. BIOS/UEFI switched sector emulation mid-life — Detect and normalise; recompute divergence on aligned geometry.

Human / Operational

31. Wrong disk removed (good pulled, bad left) — Identify the real good member by superblock events and FS logs; rebuild from that image and supplement with unique sectors from the other.

32. DIY rebuild propagated bad blocks — Discard post-rebuild writes; reconstruct pre-rebuild state by logs/journals; salvage unaffected regions first.

33. Accidental quick format of mirrored volume — Recover prior FS headers/superblocks from slack/tail; mount earlier generation RO; export files.

34. Mass deletion across the mirror — Work only on images; replay journals, parse MFT/inodes to undelete; carve unallocated extents; avoid in-place writes.

35. In-place chkdsk/fsck worsened state — Select pre-repair snapshot from images; rebuild indexes/catalogs from journals/secondary superblocks.

36. Drive order swapped in NAS bays — Less critical for mirrors than parity; still, select the most recent clean shutdown/transaction sequence; disable auto-resync.

37. Clone to smaller disk truncated data — Re-export on correct geometry; repair tail metadata; resume logical work.

38. Firmware update triggered unwanted resync — Stop writes; choose pre-update generation; heal torn sectors using logs.

39. Hot-remove mid-write (torn sectors) — Detect partial-write signatures (e.g., NTFS fixups); prefer intact copy; reconcile with journal.

40. Expired/rotated encryption keys — Open with provided keys (BitLocker/LUKS/SED); otherwise plaintext carving only, with limitations documented.

Geometry / Generation Selection

41. Gigabytes of block-level disagreement — Divergence map + FS transaction chronology to choose winner per extent; record decisions for auditability.

42. Partition misalignment (legacy cloning) — Signature search (NTFS boot sector, XFS/EXT/APFS headers) to realign; recompute divergence on aligned views.

43. Endianness/byte-order anomaly after platform move — Byte-swap virtual device; re-parse metadata; continue selection.

44. Tail metadata missing on one member — Use backup GPT/secondary superblocks from the other; rebuild the tail on export only.

45. Bitmap shows both “dirty” — Prefer the member with fewer outstanding transactions and consistent FS log; otherwise test-open strategy for structured files.

46. Clock skew between systems — Ignore wall-clock; trust monotonic transaction IDs and journal sequence numbers.

47. Bad cloning produced short images — Re-clone with full LBA and proper timeouts; repeat mirror arbitration.

48. Mixed LBAs from sector remapping utilities — Normalise mapping; ensure consistent logical geometry before FS work.

Filesystems & Volume Managers

49. NTFS: MFT/$Bitmap divergence — Replay $LogFile; rebuild indexes and security descriptors; graft orphaned files to a recovery tree; verify by open-tests.

50. NTFS: USN Journal indicates newer edits on one side — Trust that side for the edited extents; keep other side for older, consistent ranges.

51. XFS: log replay + AG B-tree damage — Replay log on images; rebuild AG trees from secondary superblocks; mount RO to extract.

52. EXT4: dirty journal & orphan lists — Journal replay; carve residual inodes; rebuild directories from .journal and backups.

53. ReFS: epoch mismatch after crash — Mount the consistent epoch/snapshot; export datasets; avoid rw mounts.

54. APFS: OMAP/container inconsistencies — Rebuild container superblocks and object map; mount the most coherent volume group; extract data.

55. HFS+: catalog/extent corruption — B-tree rebuild from alternate nodes; verify via sample open/CRC.

56. LVM PV/VG metadata loss — Carve PV headers; reconstruct VG; activate LVs read-only; fix the inner FS and export.

57. Windows Storage Spaces (two-way mirror) drift — Parse NB metadata; materialise a consistent virtual disk from slab maps; mount NTFS and extract.

58. CoreStorage/Fusion mirror component — Re-link logical volume groups; repair APFS/HFS+ inside; copy out data.

59. ZFS mirrored vdev: one side stale — Import on images (zpool import -F), prefer valid TXG chain, scrub and copy datasets/snapshots.

60. Btrfs RAID1 profile with checksum errors — Use btrfs restore to extract good extents/subvolumes; verify checksums; avoid rw mounts.

NAS-specific (Synology/QNAP/others)

61. Synology mdadm-mirror + LVM + EXT4 mismatch — Select coherent md superblocks by event; rebuild LVM; mount EXT4; export shares.

62. Synology Btrfs checksum failures — Prefer extents with valid checksums; use btrfs restore; cross-check snapshots.

63. QNAP mirror marked clean but data differs — Disable auto-resync; base selection on md events and FS journals; export from the coherent side.

64. QNAP iSCSI LUN (file-backed) damage — Carve LUN; loop-mount; repair inner FS (NTFS/VMFS/etc.) and extract.

65. NAS OS reinstall wrote fresh headers — Carve older md/LVM/ZFS headers by UUID; assemble earlier generation; mount RO.

66. SSD cache stale blocks poisoning reads — Bypass cache devices; build from HDDs; extract; rebuild cache on new hardware.

67. NAS expansion attempted during member weakness — Revert to pre-expansion generation; recover from that state; document lost growth extents if any.

Virtualisation & Applications

68. VMFS datastore header damage on mirrored LUN — Rebuild VMFS metadata; enumerate VMDK chains; mount guest FS; export VMs.

69. Hyper-V AVHDX chain broken on CSV — Repair parent/child links; merge snapshots; mount VHDX and verify app consistency.

70. KVM qcow2 overlay missing — Recreate overlay mapping with base; mount guest FS; salvage files.

71. Exchange/SQL after crash on a mirror — Replay ESE/SQL logs on the image; export mailboxes/tables; integrity-check with app tools.

72. Veeam repository on ReFS/XFS mirror corrupted — Rehydrate block store by content hash; reconstruct VBK/VIB chains; test-restore samples.

Encryption / Security

73. BitLocker over mirror (one header stale) — Unlock both; choose the decrypted side with the most recent metadata; export to a clean target.

74. LUKS/dm-crypt header damage on one side — Use backup header to open; if both damaged, raw carving only with limitations; once opened, standard FS repair on image.

75. Self-Encrypting Drives (SED) mirrored — Unlock each member via PSID/user credentials; image plaintext; continue mirror arbitration and logical recovery.

Why Reading Data Recovery

• 25 years of RAID-1 recoveries across home users, SMEs, enterprises and public sector.

• Full-stack capability: mechanical (head-stacks/motors), electronics (PCB/ROM/firmware), logical (LVM/FS/VM/DB).

• Controller-aware, forensically sound workflow; originals never written to.

• Extensive donor parts & advanced imagers to maximise readable surface and select the newest coherent generation of your data.

Next step: Package each drive securely (anti-static + padded envelope/small box) with your details/case reference and post or drop it in.
Reading Data Recovery — contact our RAID engineers today for a free diagnostic.